Archive for the ‘Do It Yourself’ Category:

2019-01-27 Replacing Corroded Battery Contacts

From FB group Building Transistor Radios 2018-01-27 Many of the radios I’ve acquired were so corroded that I had to replace metal parts. I used tin can lids to make replacement battery holder contacts. The steel is springy enough to hold cells in place. Scissors can cut the steel, and it can be drilled and

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2019-01-07 TRF Receiver Experiment

2018-01-04 also FB group Building Transistor Radios I thought that the ‘tinkerers’ who were tinkering with the loop antennas may have been getting a stronger signal because the loop antennas have a large area to capture the RF signals, so I decided to make a single channel AM Band receiver, and I chose KNX 1070

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2019-01-05 Substituting Chokes For A Coil In A Reflex Circuit

From FB group Building Transistor Radios 2018-01-15 Nick wants to use two 10 mH chokes close to each other in place of a coil that’s used in the typical reflex circuit. I’ll include a schematic of the circuit (from somewhere on the net). This is labeled L2. (begin my comment) Nick Bastian The coupling is

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2018-12-26 UHF Oscillator

I built an oscillator using the same circuit used for the FM wireless microphone. The difference is that the capacitors and inductors are much smaller in value and the 1 transistor is a 2SC3355 which can oscillate at several gigahertz. I did this to see how high a frequency I could attain with just discrete

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2018-11-26 Two 6 uH RF Chokes

from FB group Building Transistor Radios 2018-11-26 https://archive.org/stream/ETIA1983/ETI%25201983-03%2520March_djvu.txt Two 6 uH RF chokes The photo shows two different RF chokes, each about 6.4 microhenrys. The one on the left is a ferrite bead, made by Fair-Rite, Cat. # 2643000801. These were about 12 cents apiece from Mouser.com. Yes, the wire passes through the small hole

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2018-11-25 One Transistor FM Receiver Schematic Part 1

From FB group Building Transistor Radios Larry Daniel 2018-11-26 This is the original schematic posted by Larry. GM is a gimmick capacitor made of two short lengths of solid hookup wire, twisted together for a few pF capacitance. List of RF Chokes for the ham bands Larry said he used an RCA SK1008, then corrected

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2018-11-22 Homemade 9 pF Gimmick Capacitor

Also posted to FB group Building Transistor Radios Watson’s 9 picofarad homemade “gimmick” capacitor This homemade capacitor can be used for circuits were the capacitance is not critical, such as a wireless microphone for the FM broadcast band. The wire can be obtained from the cable used to connect telephone outlets. Solid (not stranded) plastic

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2018-03-02 One Transistor AM Radio

FB group Building Transistor Radios In JF1OZL’s voluminous archive I found his version of a MW receiver.  It is labeled [2] …. MW-RADIO (see link).  He used a long wire antenna, and an IF transformer with the ceramic capacitor removed for the tuning coil.  He also said to use a ferrite loopstick, which is what

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2018-01-08 RF Oscillator For AM Band

For FB group Building Transistor Radios When I started building regen receivers, the first thing I found I needed was a simple  signal generator.  I have a function generator, but every time I want a different frequency, I had to readjust the controls.  So I built a few RF oscillators to put close to the

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2017-09-01 Automated Gallows РArduino 

Suggestion for project on FB group Arduino Projects – Sept 17 Automated Gallows! A motorized winch adjusts noose. Asks for three officials to each press confirmation button. Has an emergency abort button. Counts down 5, 4, 3, 2, 1… Pulls the trapdoor latch! Monitors heartrate until no sign for 5 minutes Lights up sign “Execution

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